1. Field of the Invention
This invention relates to a tracklaying undercarriage for bulldozers, crawler loaders or other tracklaying vehicles, and more particularly to a tracklaying undercarriage that includes bearings that absorb noise and impacts and that do not require frequent servicing.
2. Description of the Prior Art
In known tracklaying undercarriages, the bearings of the tracklaying frames must be frequently serviced because the bearings transmit to the main frame, and via the latter to the driver's cab, the impacts which are applied to the chains, and also the noise which is caused by such impacts.
It is an object of the invention to provide a tracklaying undercarriage in which the tracklaying frames are connected to the main frame by bearings which do not need frequent servicing and which will absorb impacts and noise.
3. Summary of the Invention
Briefly stated, in accordance with one aspect of the present invention, tracklaying frames are mounted on supporting axles by means of elastic bearings, which have outer and inner races that are interconnected by elastic material. The use of elastic bearings in accordance with the invention affords the additional advantage that the bearings will allow for inaccuracies which are due to manufacture. The undercarriage includes a central main frame, two tracklaying frames disposed on opposite sides of the main frame and mounted at one end on mutually aligned supporting axles, which are fixed to the main frame, and at the other end on a rocker bridge, which is pivoted at its center in the main frame. The apparatus also includes track chains, which are trained around driving and reversing chain sprockets mounted at mutually opposite ends of the tracklaying frames, and rotary hydraulic motors for driving the driving chain sprockets, which motors are supplied with fluid by hydraulic pumps driven by an internal combustion engine mounted on the main frame.
Owing to the pivotal movements of the rocker bridge, the tracklaying frames perform small angular movements about vertical axes. Such movements will also be taken up by the elastic bearings, which include outer and inner races that are interconnected by elastic material.
In an embodiment of the invention, the elastic bearings are in the form of spherical bearings, which include spherical inner races and split spherical outer races, which are interconnected by vulcanization-bonded rubber interlayers. Such spherical bearings are known, they need not be serviced, and they have a high load-carrying capacity in the radial and axial directions. The rubber interlayer, which is disposed between and vulcanization-bonded to the spherical inner race and the split spherical outer race, will have a high load-carrying capacity when the outer races have been axially stressed. The outer race is capable of an elastic rotation relative to the inner race about radial and axial axes and during such rotation will impart shear forces to the rubber interlayer.
In an embodiment of the tracklaying underframe in accordance with the invention, the hydraulic motors for driving the driving chain sprockets are mounted on the tracklaying frames so that impact, vibration and noise will not be transmitted from the tracklaying frames to the main frame via the drive means.
The mounting of the hydraulic motors and the associated gear trains on the tracklaying frames affords the additional advantage that the drive means and the gear trains will not be loaded by the weight of the main frame, that the geometry of the chain-guiding means will not be loaded by the weight of the main frame, and that the geometry of the chain-guiding means will not be altered when the tracklaying frames have been swung to a position in which there is a bend in a chain because the driving chain sprocket is rotatably mounted on a sprocket shaft, which is disposed beside the supporting axle and mounted on a gear shaft connected to the main frame.